FILE - Surfers are silhouetted during sunset in the Venice Beach section of Los Angeles, California, June 16, 2021. An unusual heat wave is forecast for the coming week for northern California and other parts of the U.S. Pacific Northwest.
FILE - Surfers are silhouetted during sunset in the Venice Beach section of Los Angeles, California, June 16, 2021. An unusual heat wave is forecast for the coming week for northern California and other parts of the U.S. Pacific Northwest.

The U.S. National Weather Service (NWS) is warning that extreme heat will strike portions of the U.S. Pacific Northwest later this week, and that temperatures could exceed 37 degrees Celsius (98.6 F) for only the third time in history, in a region where many lack air conditioning.

The NWS Weather Prediction Center on Wednesday described the coming heat wave as “record-breaking and dangerous.” It is expected to impact much of Washington state, Oregon, northwestern Idaho and northern California.

The weather service says more than 80 sites are forecast to break daily high temperature records late this week, and all-time June monthly records could also be broken in some Pacific Northwest locations.

Areas of Washington state and Oregon are facing a high risk of excessive heat, particularly Saturday and Sunday, the weather service said, warning that heat-related illnesses are likely for some and expressing concern for residents without adequate air conditioning.  

The region, which usually sees very mild temperatures, is particularly poorly equipped to handle extreme heat. The Seattle Times newspaper, citing census data, says Seattle, in Washington state, is the least air-conditioned city in the U.S., with cooling systems in only about a third of its homes. Portland, in the state of Oregon, to the south, comes in third.

The NWS predicts that the heat wave will extend into next week. More than 55% of the western U.S. is experiencing an extreme or exceptional drought, according to The Washington Post.